Matt Stevens was losing his family. And being no stranger to failed relationships, it came as no surprise to Matt when threats of divorce turned into plans to divorce his wife, Grace. The plan was simple: just make it through Christmas so their two teenage children could have one more holiday with their parents together. But when Matt and Grace drink the contents of a mysterious gift left behind at their annual Christmas ball, they find themselves transformed into younger versions of themselves―the same ages as their adolescent children. At a time when their faith in each other is at its weakest, now-teenage Matt and Grace―along with their own adolescent children―must put their differences aside, find trust in each other, and embark on a dangerous, cross-city journey to find answers and an antidote before time runs out.